UBLOX NEO6-M GPS via hardware serial to NodeMCU(ESP8266)

Hey there,
I´am working with NodeMCU Board (ESP12E) and am trying to connect the GPS modul to the hardware serial port.
For debugging purposes I installed a telnet server and power can be supplied via VIN-pin, so the USB-connection isn´t used, once I uploaded the sketch.
But shouldn´t I be able to read the GPS data like this:

while(Serial.available)
{
gps.encode(Serial.read());
}

where

gps.encode()

is the gps object using the encoding function for NMEA-sentences provided by TinyGPS++ library.

First I only need a short answer, if this is technically possible. I´ve got my problems, understanding the link between USB and UART0. I understood, that using both at the same time is not possible, but thought it would be possible to use UART0 (= RX/TX means GPIO3/GPIO1), when USB is not in use.

First I only need a short answer

OK. The answer is yes.

You need to explain what the problem really is. If you are using the hardware serial port to read the GPS (and, for some foolish reason, throwing away the valuable information that encode() returns), how do you KNOW what the program is doing?

Obviously, you can't use Serial.print() for debugging.